JP2021510834A - Transmitter for transmitting light - Google Patents

Abstract

The present invention relates to a transmitting device for transmitting light at at least one frequency, the transmitting device is configured to emit light to a plurality of different angular ranges, and the frequencies of the light in each of the plurality of angular ranges are different. It is configured so that it is varied over time within a frequency range and that frequencies within a plurality of different frequency ranges for different angle ranges do not overlap at different times.

Description

The present invention relates to a transmitter for transmitting light of at least one frequency.

The present invention also relates to a receiving device for receiving light.

Furthermore, the present invention relates to a sensor device, a method of transmitting light of at least one frequency, and a method of receiving light of a plurality of different frequency ranges.

Although the present invention is applicable to any transmitting and receiving device, the present invention will be described in the context of a photodetector and ranging system, i.e. lidar.

Known lidar systems use narrowband laser beams that are deflected in a particular direction. When the laser beam hits an object, the distance to the object can be determined based on the reflection of the laser beam at that angle on the object. For this purpose, for example, a linear frequency lamp (frequency-modulated continuous wave) is transmitted based on the FMCW principle, and coherent reception determines the frequency difference between the transmitting lamp and the receiving lamp. The distance to the object can be determined based on this frequency difference. The area can be illuminated two-dimensionally so that objects within the area can be detected. A short measurement time is required for this purpose, which usually shortens the measurement range, that is, the distance at which an object can be detected. The reason is that as the distance increases, the signal-to-noise ratio for a particular distance linearly depends on the measurement time, and as the measurement time increases, measurement is no longer possible.

In addition, it is known to use multiple sensors to detect a particular angular range, and each sensor is assigned a separate angular region of the angular range. However, in this case, a separate transmission / reception route is required for each area. In addition, multiple reflections may arise from other angular regions.

In one embodiment, the invention provides a transmitter for transmitting light of at least one frequency, the transmitter being configured to emit light over a plurality of different angular ranges (100, 101). The frequency of each light in the plurality of angle ranges is changed with time in each frequency range, and the frequencies in a plurality of different frequency ranges for different angle ranges are configured so as not to overlap at different times.

In a further embodiment, the invention provides a receiver for receiving light, a separator for separating frequencies in a plurality of different frequency ranges that change over time, and converting the received light into an electrical signal. At least one detector for this is arranged.

In a further embodiment, the present invention comprises a sensor device having the transmitting device according to at least one of claims 1 to 6 and the receiving device according to any one of claims 7 to 9. provide.

In a further embodiment, the invention provides a method for transmitting light of at least one frequency, the light is emitted into a plurality of different angular ranges, and the frequencies of the light in each angular range are within their respective frequency ranges. It changes over time to ensure that frequencies within multiple different frequency ranges for different angular ranges do not overlap at different times.

In a further embodiment, the invention provides, in particular, a method of receiving light in a plurality of different frequency ranges transmitted by the method of claim 11, in which frequencies in a plurality of different frequency ranges that change over time are separated. In particular, the received light is converted into an electrical signal.

In other words, the transmitting device may transmit the light to a plurality of different angular ranges, and the reflected light may be received again by the receiving device.

One of the advantages is that a plurality of angular ranges can be simultaneously irradiated without requiring a plurality of transmitters and / or a plurality of receivers, that is, a plurality of transmission / reception paths. Another advantage is that in this way the measurement time to change each frequency range is increased, which can improve the signal-to-noise ratio, which is ultimately the object by the sensor device. Will increase the measurement range when is detected. Yet another advantage is that, for example, several horizontal planes can be irradiated simultaneously, increasing flexibility.

Further features, advantages, and further embodiments of the present invention will be described and clarified below.

According to an advantageous further embodiment, the transmitter is configured to change the frequency in each of the angular ranges linearly over time, preferably from the start frequency to the end frequency. One of the advantages achieved by this is that it allows for simple changes in frequency over time over the entire frequency range. In addition, it allows for clear time allocation of frequencies, which simplifies later evaluations.

According to a further advantageous embodiment, a light source and a modulator for generating a time-dependent change in the frequency of the light from the light source are arranged. The modulator allows light from a light source, such as a laser, to be easily and simultaneously reliably modulated.

According to a further advantageous embodiment, the modulator comprises a modulator for each of the different frequency ranges. This allows for particularly reliable modulation.

According to a further advantageous embodiment, the modulator has a modulator for changing the frequency range over time and at least one additional modulator for generating a plurality of different frequency ranges. One of the advantages achieved in this way is that the separation of frequency ranges and the time variation of each of the frequency ranges can provide a particularly reliable change in frequency in different frequency ranges. For example, a phase modulator can generate frequency offsets between different ranges. In this case, the phase is modulated to change over time, which produces a frequency offset. Examples of such modulators are those based on charge carrier density modulation or based on electro-optical effects such as the Pockels effect or the Kerr effect.

According to a further advantageous embodiment, separate light sources are arranged for each frequency range. In this way, different light sources with different characteristics can be used, which increases the flexibility as a whole.

According to a further advantageous embodiment, separate detectors are arranged for each frequency range. Therefore, the detector can be adapted to the received light in each frequency range, and particularly reliable light detection can be achieved.

According to a further advantageous embodiment, the separator has a notch filter, especially in the form of an optical ring oscillator. A notch filter can be used to reliably separate received light with different frequency lamps into light with one frequency lamp each.

Further important features and advantages of the present invention become apparent from the dependent claims, drawings and description based on the drawings.

It goes without saying that the above-mentioned features and the features described below can be used not only in the specified combination but also in other combinations or alone without departing from the scope of the present invention.

Preferred configurations and embodiments of the present invention are shown in the drawings and detailed in the following description, the same reference symbols relating to the same or similar, or functionally identical components or elements.

It is a time-frequency representation indicating a time change of frequency according to the first embodiment of the present invention. It is a figure which shows the transmission device by the 2nd Embodiment of this invention. It is a figure which shows the transmission device by the 3rd Embodiment of this invention. It is a figure which shows the transmission device by 4th Embodiment of this invention. It is a figure which shows the transmission device by 5th Embodiment of this invention. It is a figure which shows the receiving apparatus by the 6th Embodiment of this invention. It is a figure which shows the receiving device by 7th Embodiment of this invention. It is a figure which shows the sensor device by 8th Embodiment of this invention.

FIG. 1 shows a time-frequency representation of the temporal change in frequency according to the first embodiment.

FIG. 1 shows the time-frequency representation of the frequency lamp, where the baseband of the top frequency lamp 6c is shown by a broken line. In detail, FIG. 1 shows time-frequency representation 1, with frequency 3 plotted against time 2. Three frequency lamps 5a, 5b, 5c are shown, each rising at the same time interval and with the same gradient. The frequency lamps 5a and 5b differ in their starting frequencies by a frequency difference of 4a, and the two frequency lamps 5b and 5c differ by a frequency difference of 4b. The frequency differences 4a and 4b may be the same or different. In Figure 1, the start frequency ^f _{a START} of the first lamp 5a has the lowest starting frequency ^f _{c START} third frequency lamp 5c is highest. Due to the linear rise, the respective end frequencies _fa ^{, b, c} END of each frequency lamp 5a, 5b, 5c are higher than the respective start frequencies ^{fa, b, c,} _START. Of course, an inverted frequency lamp or a frequency lamp that descends linearly is also possible. Although three frequency lamps 5a, 5b, and 5c are shown in FIG. 1, any number of other frequency lamps are possible.

The frequency lamps 5a, 5b, and 5c can be generated by the following methods. Light from a light source, such as a laser, is generated by three different phase modulators and the three linear frequency lamps 5a, 5b, 5c are modulated. Three frequency lamps 5a, 5b, 5c, the start frequency _{^{f a START, f b START =}} f a START + Δf 1, depends _{^{f c START = f a START +}} Δf 1 + Δf 2, different starting frequency _{f START, f} START + _{Δf The offset frequencies 4a and 4b between 1} , f _START + Δf ₁ + Δf ₂ are frequency deviations, that is, the difference between the start frequency and the end frequency of each of the frequency lamps 5a, 5b and 5c f ^{a, b, c} _ENDE − f ^{a, b, c It} does not necessarily have to be larger than _STAR. The frequency lamps 5a, 5b, 5c can be mixed into their respective basebands 6 upon reception, which is known as so-called "decharping". In this case, the modulation is released and the frequency lamps 5a, 5b and 5c are separated. As long as the basebands 6 are sufficiently separated from each other in terms of frequency, the frequency lamps 5a, 5b, and 5c may be at least partially located in the same frequency range, as long as the basebands do not overlap. In this case, the frequency in a certain frequency range at a certain time point is different from the frequency in another frequency range. FIG. 1 shows only the baseband 6c of the top frequency lamp 5c. In general, instead of other forms of frequency change, such as the linear ascent in FIG. 1, a linear ascent followed by a linear descent is also possible.

FIG. 2 shows a transmitter according to the second configuration of the present invention.

FIG. 2 shows a transmitter 21 including three modulators 11 and a light source in the form of a laser 10. The laser 10 sends light at a specific frequency f _START, which is modulated by three modulators 11a, 11b, 11c to produce linear frequency lamps 5a, 5b, 5c. In other words, one modulator 11a, 11b, 11c modulates the frequency lamps 11a, 11b, 11c, respectively. After that, the generated light of the three frequency lamps 5a, 5b, and 5c is emitted by the transmission optical system 12.

FIG. 3 shows a transmission device according to a third embodiment of the present invention.

FIG. 3 shows a transmitter 21 including a laser 10, a modulator 11a for generating a frequency lamp, and two modulators 11b, 11c for generating frequency offsets 4a, 4b. Here, only one modulator 11 is used to generate the frequency lamps 5a, 5b, 5c. The linear frequency lamp generated by the modulator 11 with respect to the light of the laser 10 is then branched into three paths 5a, 5b and 5c, with frequency offsets 4a and 4b in two of the three paths 5b and 5c. Only shifts are made. The frequency offsets 4a and 4b can also be generated by a phase modulator. The phase is modulated to change over time, which produces frequency offsets 4a and 4b. Such modulators are based, for example, on charge carrier density modulation or electro-optic effects such as, for example, the Pockels effect or the Kerr effect.

FIG. 4 shows a transmission device according to a fourth embodiment of the present invention.

FIG. 4 essentially shows the transmitter 21 according to FIG. Unlike the three modulators 11a, 11b, 11c of FIG. 2, the modulator 11 shown in FIG. 4 has a wide band so that all three frequency lamps 5a, 5b, and 5c can be modulated with respect to the light of the laser 10. It is configured.

FIG. 5 shows a transmission device according to a fifth embodiment of the present invention.

FIG. 5 essentially shows the transmitter 21 according to FIG. Unlike the transmitter 21 according to FIG. 2, the transmitter 21 shown in FIG. 5 is equipped with three lasers 10a, 10b, and 10c, and the modulators 11a, 11b, and 11c assigned to these lasers 10a, 10b, and 10c, respectively. Accordingly, the frequency _{f START, f 'START, f} '' optical signal _START frequency lamp 5a, 5b, given by 5c. Next, the corresponding modulated light having the frequency lamps 5a, 5b, 5c is emitted together via the transmitting optical system 12.

As shown, the modulated optical signals shown in FIGS. 1 to 5 are radiated into space via the transmission optical system 12. In this case, for each modulated optical signal, an individual transmission optical system 12 in the form of, for example, a micromechanical scanner or an optical phase array can be arranged, and the transmission optical system 12 emits light in a predetermined angle range. The different angular ranges of / additional transmission optics do not overlap. Alternatively, the transmitter 21 may be configured such that different frequency ranges, especially the average wavelengths of the different lamps 5a, 5b, 5c, are automatically radiated by the transmitting optical system 12 into different angular ranges. Then, the respective lights of the three modulated laser beams 10a, 10b, and 10c of FIG. 5 are combined and emitted through the same transmission optical system 12. Multiple different frequencies of the modulated light result in the desired beam deflection to multiple different solid angles. The embodiment of FIG. 5 is particularly advantageous for this purpose, as the frequency offsets 4a, 4b between the lamps 5a, 5b, and 5c are chosen to be large enough.

FIG. 6 shows a receiving device according to a sixth embodiment of the present invention.

FIG. 6 shows a receiver 22 with three detectors 15a, 15b, 15c. The light received by the receiving optical system 13 of the receiving device 22 is first separated by the separating device 14 before reaching the detectors 15a, 15b, and 15c. In other words, before mixing, i.e. before converting the optical signal into an electrical signal, the received optical signal containing the plurality of frequency lamps 5a', 5b', 5c' is, for example, a notch filter, especially in the form of an optical ring resonator. Separated through. The frequency lamps 5a', 5b', and 5c'are supplied to the detectors 15a, 15b, and 15c, respectively. Prior to this, each reception frequency lamp 5a', 5b', 5c'is superimposed on the corresponding transmission lamps 5a, 5b, 5c to ensure coherent reception. More precisely, after the light of the corresponding frequency lamps 5a', 5b', 5c'is detected by the corresponding detectors 15a, 15b, 15c, the respective frequency lamps 5a', 5b', which are superposed in this way, The optical signal of 5c'can be mixed with the corresponding transmit lamps 5a, 5b, 5c to form baseband 6, respectively, and then evaluated by a known method according to the FMCW principle.

FIG. 7 shows a receiving device according to a seventh embodiment of the present invention.

FIG. 7 shows a receiver 22 with a detector 15. The light received by the receiving optical system 13 is supplied to a detector 15 having, for example, one or two photodiodes. Then, the light of any one of the received frequency lamps 5a', 5b', and 5c'is superimposed on the light of the corresponding transmission lamps 5a, 5b, and 5c. Subsequently, all basebands 6, i.e. all basebands 6a, 6b, 6c having transmitted frequency lamps 5a, 5b, 5c, respectively, with frequency lamps 5a', 5b', 5c'can be sampled, or , Bandpass filters and / or electric mixers can be used to separate the frequency lamps 5a, 5b, 5c at each baseband 6. In particular, since the frequency differences 4a and 4b of the frequency lamps 5a, 5b and 5c with respect to the bandwidth of the detector 15 are appropriately selected, the detector 15 is configured to receive all the lamps 5a, 5b and 5c. ing.

FIG. 8 shows a sensor device according to an eighth embodiment of the present invention.

FIG. 8 shows a sensor device 20 in the form of a rider system. The sensor device 20 includes a transmission device 21 according to the embodiment of FIG. 1 and a reception device 21 according to the embodiment of FIG. The transmitting device 21 emits light having different frequency lamps 5a and 5b to different angle ranges 100 and 101. The object 30 located within the measurement range of the sensor device in the angle range 100 reflects the synchrotron radiation of the frequency lamp 5a. Next, the light of the frequency lamp 5a'reflected by the object 30 is received by the receiving device 22. Next, the sensor device 20 can evaluate the received light and determine the distance of the object 30 from the sensor device 20.

In summary, at least one of the embodiments of the present invention has at least one of the following advantages:
-Simultaneous transmission to multiple different angle ranges and reception of reflected light by only one receiving unit,
・ Simultaneous irradiation of multiple angle ranges,
・ Expansion of measurement time for each lamp and improvement of signal-to-noise ratio due to this,
・ Wider measurement range,
・ The rider system can be parallelized,
・ There are few false positives due to multiple reflections, and it is highly reliable.
・ Simple structure,
-Easy implementation.

Although the present invention has been described based on preferred exemplary embodiments, the invention is not limited thereto, but rather can be modified in various ways.

Claims (12)

A transmitter (21) for transmitting light of at least one frequency, which is configured to emit light to a plurality of different angular ranges (100, 101), and each of the angular ranges (100, 101). frequency of the light, each of the frequency ranges ^{_{(f a START, f a ENDE}} , f b START, f b ENDE, f c START, f c ENDE) with is varied depending on the time, different angular ranges ( a plurality of different frequency ranges _{^(f a} START against ^{_{100,101), f a ENDE, f}} b START, f b ENDE, configured so as not to overlap with _{f c} ^START, _{f c ENDE)} frequency different times in the (2) Transmission device (21). A transmission device according to claim 1, wherein the angular range (100, 101) so as to linearly change with frequency (3) time at each preferably starting frequency _{^(f a START,} ^{f b} _START, ^f _{c START)} from the end frequency ^{_{(f a ENDE, f b ENDE}} , f c ENDE) configured transmission device to change to. The transmitter according to claim 1 or 2, which generates a time-dependent change in the frequency of light of a light source (10, 10a, 10b, 10c) and the light source (10, 10a, 10b, 10c). A transmission device in which a modulation device (11, 11a, 11b, 11c) is arranged. A transmission device according to claim 3, wherein the modulator (11, 11a, 11b, 11c) are different frequency ranges ^{_{(f a START, f a ENDE}} , f b START, f b ENDE, f c START, modulator for each of the f ^c _ENDE) containing (11a, 11b, 11c), the transmission device. The transmitter according to claim 3, wherein the modulator is a modulator (11a) for changing the frequency range over time, and at least one additional modulator for generating a plurality of different frequency ranges (11a). A transmitter having 11b, 11c). A transmission device according to any one of claims 1 to 5, each frequency range ^{_{(f a START, f a ENDE}} , f b START, f b ENDE, f c START, f c ENDE) for A transmitter in which separate light sources (10a, 10b, 10c) are arranged. A receiving device (22) for receiving light, particularly a transmitting device (21) according to any one of claims 1 to 6, and receiving the transmitted light (22). And
A plurality of different frequency ranges change over time ^{_{(f a START, f a ENDE}} , f b START, f b ENDE, f c START, f c ENDE) separation apparatus for separating the frequency (3) and (14) The receiving device (22) is provided with at least one detector (15, 15a, 15b, 15c) for converting the received light into an electrical signal. The receiving apparatus according to claim 7, separate detector (15a, 15b, 15c) is the frequency range ^{_{(f a START, f a ENDE}} , f b START, f b ENDE, f c START, f c ENDE ) Are arranged for each receiver. The receiving device according to claim 7 or 8, wherein the separating device (14) has a notch filter in the form of an optical ring oscillator in particular. The transmitting device (21) according to at least one of claims 1 to 6.
A sensor device (20) including the receiving device (22) according to any one of claims 7 to 9. A method of transmitting light of at least one frequency (3).
Each frequency range multiple different angular range (100, 101) each of the frequencies of light according to ^{_{(f a START, f a ENDE}} , f b START, f b ENDE, f c START, f c ENDE) within a time varying Te (5a, 5b, 5c), different angular ranges a plurality of different frequency ranges for ^{_{(100,101) (f a START,}} f a ENDE, f b START, f b ENDE, f c START, f c ENDE) A method of emitting light to a plurality of different angle ranges (100, 101) so that the frequencies in the frequency do not overlap at different times (2). A method of receiving light in a plurality of different frequency ranges, particularly a method of receiving light emitted by the method according to claim 11.
A plurality of different frequency ranges change over time ^{_{(f a START, f a ENDE}} , f b START, f b ENDE, f c START, f c ENDE) separating the frequency (3) in (14), in particular the reception A method of converting the emitted light into an electrical signal.

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